Schertle writes unoriginal make-believe (Hob Goblin and the Skeleton, The April Fool), and this, correspondingly, is unimaginative make-believe play--pictured with some skill, but little involvement, in flat, collage-like color-areas. ""When I'm up in my treehouse,"" begins the little-girl narrator, ""I'm all alone. Just me, myself, and I.' How the book misses, you can see right there. In one sense, the statement is obvious and uninteresting; in another, it's both insensitive and inaccurate. In the very picture opposite, we see a bird; and the next sentence is about luring birds to build a nest. On succeeding pages we'll hear about ants who regularly visit the treehouse, and about the little girl's car, who does too. So she isn't really alone--and she especially isn't alone in the child's sense of turning a tree house into a self-contained, imaginary world. Its components, in turn, are stock items--including a treasure (22 polished pennies ""wrapped inside a sock that's inside a jelly jar that's right underneath my treehouse tree"") which the narrator supposedly protects from enemies by keeping a lookout with a spyglass. Real children are more ingenious and more realistic than this.